Late Saturday afternoon what appeared to be a stick of dynamite (or a firecracker) was thrown at the window of a business on the 300 block of Grant Street near Union Square, causing some minor damage and snarling traffic along Sutter for a bit. Witnesses saw two suspects fleeing the scene, and one witness even snapped a photo of them, aiding police in making one arrest. One suspect is still at large.

According to SFPD spokesman Officer Albie Esparza, the explosive device was a small firework.

As ABC 7 reports, a window was shattered and a planter box was damaged, but that seems to be the extent of it. The targeted business has not been revealed.

No motive for the attack is yet known.